H-Y (male-specific) antigen appears to play important roles in gonadal organogenesis, in reproduction and in clinical transplantation. Detailed study of these functions has been hindered by the lack of a simple method for the detection of H-Y antigen and its localization at a cellular or subcellular level. Furthermore, H-Y antigen has never been purified and subsequently all currently available antisera are of necessity prepared in inbred strains of mice. The objectives of this project are thus to obtain preliminary physico-chemical information concerning H-Y antigen so that purification can be achieved from a suitable human tissue source, and antisera raised using the purified material. The project involves three major phases. Firstly, a variety of male tissues and male-derived cell lines will be screened for the presence of H-Y antigen using our fluorescence microscopy technique with appropriately absorbed mouse H-Y antisera. Secondly, extraction will be made of selected tissues and purification of H-Y antigen will be attemped using a combination of ioselectric focusing and affinity chromatography. Thirdly, the resultant purified preparation of H-Y antigen will be used to immunize virgin female rabbits. Such antisera, after absorbtion with female tissues to remove contaminating specificities, should contain H-Y antibodies at high titer.